If you have watched a Grand Slam tennis tournament in the past decade, you are probably aware that the game is dominated by just a few international powerhouses. At the conclusion of each tournament, it is likely that you will see Serena Williams atop the women's podium and a member of the Big Four--Roger Federer, Rafael Nadal, Novak Djokovic, and Andy Murray--hoisting the trophy for the men. And while there is not a lot of variety in the outcome of these matches, the game of tennis itself has changed drastically over the decades, as developments in technology and conditioning regimens, among...